Feng, Rehabilitation of Stress-Induced Insomnia 1 Abstract The goal of this project is to evaluate and compare how the acute treatment with hypnotics that have different mechanisms would improve sleep and suppress the brain levels of corticotropin-releasing hormone (CRH) and the orexins which are involved in the neurobiological pathology for insomnia, and to evaluate whether a long term treatment with several different hypnotics would eventually rehabilitate both the sleep disorder and the neurobiological abnormalities in a chronic rat model of insomnia. We propose two objectives to separately study how the drugs eszopiclone (Lunesta, a non-benzodiazepine GABAergic agonist) and trazodone (a commonly prescribed antidepressant used for insomnia) affect sleep in acute (two days) treatment and chronic treatment (two weeks), and whether these drugs suppress hypothalamic CRH and orexins directly by acute brain infusion and indirectly by chronic systemic treatment. All experiment will be conducted in a rat model of chronic insomnia induced by neonatal maternal deprivation in comparison to that in control subjects. Four major techniques will be applied. This includes (1) to us a rat model of insomnia induced by the neonatal maternal deprivation, (2) polysomnographic recording, a classic technique for sleep evaluation, (3) microdialysis for extracellular fluid collection and (4) use radioimmunoassay to quantify the levels of CRH and orexins. We have sufficient preliminary data in support of the feasibility of using these techniques. Clinical significance We propose two objectives for this project: to answer the key questions of whether short term or long term treatment with different types of hypnotics would recover the abnormalities of sleep and the neurobiological markers in the chronic model of insomnia. The successful completion of the project would allow us to outline the immediate and the chronic effects of treatment with eszopiclone and trazodone on sleep and brain CRH and the orexins, and to correlate the immediate effect of these drugs on hypothalamic CRH and the orexins with the long term efficacy of insomnia treatment. These results would be able to help in improving the current understanding in the treatment strategy for chronic insomnia. Relevance of the Proposed Work to the VA Patient Care Mission Insomnia is a common disorder in the general population in the United States and chronic insomnia is present in 70% of those with PTSD. It leads to impaired next-day functioning and psychological distress, and is a predictor of later increased depression risk. Successful completion of the study of orexinergic involvement in the pathological regulation of hyperarousal in insomnia will provide important new insights into the neurobiological regulation of insomnia, and may provide new directions for its treatment.